Heretofore, bus bars, produced by punching an electrical conductive material, are contained as internal circuits in an electrical connection box such as a junction box or the like.
For convenience of explanation, a conventional connection structure between bus bars and relay terminals will be described by referring to FIG. 3. FIG. 3 is an exploded perspective view of a conventional electrical connection box for an automobile.
As shown in FIG. 3, an electrical connection box 1 includes a casing with an upper casing member 2 and a lower casing member 5. Bus bars 4 and insulation plates 3 are alternately laminated on each other in the casing. An end of each bus bar 4 is bent to form a tab 4a. The tabs 4a penetrate a connector containing section 2a in the upper casing 2, a fuse containing section 2b, and a relay containing section 2c either directly or through intermediate terminals to connect with a connector C coupled to a wire harness W/H, a fuse F, and a relay R.
The bus bars 4, which constitutes the internal circuits, are made of a copper-based metal plate having high electrical conductivity. After punching the copper-based metal plate into the bus bars 4, having desired circuit configurations, a desired end of each bus bar 4 is bent to form a tab 4a. 
Recent requirements encourage recycling of junked automobiles. Iron makes the highest percentage of an automobile. When junked automobiles are incinerated to recover and recycle iron, the required mixing rate of copper to iron should be less than 0.1%. This prevents the iron from being denatured due to a reaction with the copper.
Since the bus bars 4 are made of the copper-based metal plate, as described above, it is preferable to remove the bus bars 4 from the car body upon disassembly of the automobile and to separate the bus bars 4 from the iron based car body. However, the electrical connection box must be disassembled in order to take out the bus bars from the box. This work requires extensive manpower and is not practical.
To avoid interference during iron recovery, from a practical recycling standpoint, the bus bars should be formed from an aluminum-based metal which does not denatured the iron. However, since aluminum-based metal is low in hardness and stiffness, a mating relay terminal T tends to widen the tab 4a′ provided with a press contact slot, as shown in FIG. 4. This lowers the reliability of the electrical connection. Also, a connection part between the bus bar 4′, made of the aluminum-based metal, and the relay terminal T, made of the copper-based metal, will suffer from electric erosion if any water infiltrates the connection part.